Dr. Julie, a.k.a. Scientific Chick, brings you insights into what's happening in the world of life sciences. Straight from the scientific source, relevant information you should know about, in plain language.

Monday, April 27, 2009

You’ve heard of Atkins. You’re familiar with Weight Watchers. You probably know about the South Beach Diet. Well, there’s a new diet in town, and it’s called the “Longevity Diet”. It’s inspired by a relatively new hot topic in the life sciences called caloric restriction. As the name implies, it essentially means eating less, and it's hailed not so much as a weight loss strategy as an anti-aging solution. While I’m usually excited about new simple ways of changing daily habits to live a healthy life, this one I’m not sold on yet. You may remember that I like cheese. You may also remember that I like brownies. So obviously, I’m not too excited to hear that eating less is extra healthy. Especially since most caloric restrictions studies suggest you have to cut back anywhere from 30% to 60% of what you eat to see an effect.

So far, most of the really convincing data on caloric restriction slowing down the aging process have been carried out in model organisms that fit in your pocket: rats, mice, worms, all the way down to the tiny yeast. I personally would be reluctant to extrapolate those findings to humans. Surely worms don’t have the same kind of relationship with brownies that I do. However, one recent study looks at caloric restriction in healthy humans, and it’s hard not to take notice.

Researchers from Germany took 50 normal-to-overweight elderly subjects (sorry, Mom, in this case, “elderly” means 60ish, but the important thing is to be young at heart!) and divided them into groups. One group was told to not change their eating habits, and one group was put on 30% caloric restriction for 3 months. Before the study and after the 3 months, everyone’s memory was tested using simple tests like remembering a list of words. Well, I’m very sorry to say, but after 3 months, the group who ate less did significantly better at the memory tests. Sad but true.

During the study, the volunteers were monitored for many different biological indicators (such as cholesterol, insulin, inflammation, and cellular stress), in hopes of identifying the mechanisms responsible for the effects of caloric restriction. The one mechanism that really stood out and that showed a solid correlation with the memory improvements is insulin: the group on caloric restriction had lower insulin levels. Insulin is a hormone responsible for taking the sugar out of your blood and storing it in your liver and muscles to use when energy is needed, but it also plays an important role in keeping your brain healthy. When you have less insulin circulating in your body, you become more sensitive to it, and this sharpens and improves how your body (including your brain!) reacts to insulin. This may be why the group who ate less performed better on the memory tests.

So, throw out the cheesecake? I’m going to wait a little before I draw any solid conclusions, as there is still a very ongoing debate over caloric restriction. One side is claiming significant benefits like longevity, healthy aging and protection against age-associated diseases (think Alzheimer’s). The other side is critical of the methods and models used, as well as the contradictory results, and points to the downsides of caloric restriction, especially during the reproductive years. Not eating enough can also lead to the breakdown of muscles (and remember, your heart is a muscle), which is very important to consider if you have an active lifestyle. Interestingly, in this study, the authors show that the caloric restriction group lost a significant amount of weight, but did not lose body fat. Healthy? I think the jury is still out, but hopefully more well-controlled human studies will shed some light on this potentially exciting and easy way to fend off the effects of the ticking clock.

Sometimes you have to take a step back and ask, "Is a life without brownies and cheese really worth living?" Since discovering the awesome brownies in the ISU cafes and my mom accidentally discovering how to make the best brownies in the world my answer to that question is no.

About Me

Dr. Julie is an Assistant Professor of Neurology at the National Core for Neuroethics and the Djavad Mowafaghian Centre for Brain Health at the University of British Columbia. She holds a PhD in Neuroscience.